grub / grub2 conflicts

Doug Ledford dledford at
Mon Sep 19 19:33:08 UTC 2011

----- Original Message -----
> On Mon, Sep 19, 2011 at 02:53:11PM -0400, Doug Ledford wrote:
> > This is incorrect.  The whole reason the stage1.5 portion is an fs
> > compatible reader is so that you can update the stage2 file and it
> > will pick the changes up without needing to be reinstalled.  This
> > is
> > also born out by the fact that on package update, there is no %post
> > action in the spec to reinstall the mbr and stage 1.5 files even
> > though the stage2 file likely just changed.
> We never update the stage 2 file without reinstalling the mbr and
> stage
> 1.5. The output of rpm -qf grub may be instructive.

Which has it's own gotchas.  I never use grub-install as it does the wrong things in certain circumstances.  I always manually run grub then do the install command myself.  In my case, after a grub update, I'm going to end up with a newer MBR but older stage1.5 and stage2 files because I didn't know I needed to copy them from /usr/share after an rpm upgrade.

> > > I don't see where compatibility issues come into it. If
> > > you're using the code as you're meant to use the code then you'll
> > > always
> > > be safe. If you're not, it's not guaranteed to be safe.
> > 
> > Like I said, not true.  The grub package is designed to be
> > updateable
> > without requiring an mbr reinstall.  What's more is I had a look at
> > the stage1.[hS] files in the grub shipped in FC-1 and RHEL-5, and
> > just
> > like I said, they are indeed binary compatible.  So even if the
> > grub
> > user space application pulls its MBR from a statically linked copy
> > of
> > the MBR, it will still work with pretty much any stage1.5 or stage2
> > you find in a guest.
> The grub package (as provided in Fedora) is not designed for that.
> This
> would be a much easier discussion to have if you stopped describing
> things that are manifestly true as "not true". And while it is the
> case
> that grub *is* binary compatible between every version we've ever
> released, it is *not* guaranteed that that remains true, or even that
> it's true between us and any distribution that may be installed in a
> guest.

I never said it was guaranteed, just that it was highly likely.  And for the stage1 loader, I stand by that.  For the stage1.5 and stage2 loaders, they are installed as a pair by the grub install command I sent out in this thread and so incompatibilities between them are taken care of.

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